WM Synthesis of Salicylic Acid and Aspirin

It is better to synthesise medicines in the lab rather than continuing to extract it from trees or plants because:

• Supply may be seasonal
• Supply may be weather dependant
• Extraction from natural resources gives low yield

Aspirin (made by esterification)

• Is an ester
• Functional group: RCOOR
• Alcohol + Acid ----> Ester
• It is not very soluble in water so it became the first medicine to be sold as tablets

Recrystalisation: Purifying technique

You can only make phenols into esters using acyl chlorides or acid anhydrides.

Recrystalisation

You need a solvent in which the solid is very soluble…